The most common inorganic arsenic species found in natural water under anoxic and oxic environments include arsenite (III) and arsenate (V), respectively. Dissolved inorganic arsenic in water is toxic to humans. Studies suggest that arsenite is more toxic than arsenate to humans; long-term exposure to drinking water containing arsenic in excess of 50 μg/L causes increased occurrences of skin, lung, bladder, and kidney cancer resulting in premature death. Widespread occurrence of natural arsenic (As) in groundwater has been reported from many parts of the world. The health of millions of people is at risk due to exposure to unsafe levels of arsenic in groundwater. The World Health Organization (WHO) and U.S. EPA recommend 10 μg/L of arsenic as the limit for human drinking water.
Global awareness of arsenic contamination of drinking water supplies has skyrocketed during the 1990’s when more than 35 million people in Bangladesh and West Bengal, India were inadvertently poisoned by drinking arsenic contaminated water. Further studies illustrate that elevated levels of naturally occurring arsenic in groundwater is a prevalent problem affecting many regions of the world.